SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 SD3

2021 SD3

2021 SD3 is an Aten-type near-Earth asteroid whose orbit lies mostly inside that of Earth, with a semi-major axis of 0.977 AU and a period of 0.97 yr.

Aten Observations: 23
Orbital Period · P
0.97 yr
v(q)
35.6 km/s
v(Q)
25.5 km/s
Diameter · ≈
0.03 km
TJ
6.18
Eccentricity · e
0.1658

Orbit and dynamics

Between its closest point (0.815 AU) and its farthest (1.139 AU), the heliocentric distance changes by 0.324 AU over every revolution.

One full revolution takes 0.97 yr (353 days), computed from the semi-major axis of 0.977 AU.

An eccentricity of 0.166 makes the orbit moderately elongated.

The orbital plane is tilted 6.29° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 35.6 km/s at perihelion and falls to 25.5 km/s at aphelion.

Because q < 1 AU and Q > 1 AU, this orbit geometrically intersects the region of Earth's orbit.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 25.12 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.03 km.

Observation record and orbit quality

Astrometry from 23 individual observations underpins this orbit; the fit leaves an RMS residual of 0.5046 arcseconds.

Condition code U = 5 indicates a moderately constrained orbit; predictions decades ahead still carry noticeable uncertainty.

About these computed values

Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Orbital Parameters

Semi-Major Axis
0.9769 AU
Eccentricity
0.1658
Perihelion
0.815 AU
Aphelion
1.13887 AU
Inclination
6.29°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
76.6°

Orbit diagram

The Sun sits at the focus (orange). Earth's orbit is the grey circle at 1 AU. The red dot marks the object's position at the catalog epoch.

3D orbit (interactive)

Drag to rotate; scroll or pinch to zoom. The Sun is at the focus (orange), Earth's orbit is the grey ring at 1 AU, and the red dot marks the object's current position.

Close approaches

Predicted close approaches to Earth, from NASA's Center for Near-Earth Object Studies (CNEOS).

Date (UTC)Miss distanceVelocity
2047-Sep-13 17:49 0.402516 AU
60215508 km
17.46 km/s
2048-Sep-05 18:03 0.198487 AU
29693270 km
11.29 km/s
2049-Sep-05 20:09 0.050758 AU
7593284 km
5.69 km/s
2050-Jun-18 10:37 0.197057 AU
29479308 km
5.21 km/s
2050-Oct-20 01:57 0.148723 AU
22248630 km
5.13 km/s
2051-Apr-29 17:34 0.198052 AU
29628229 km
6.73 km/s
2051-Dec-14 06:17 0.158615 AU
23728412 km
4.19 km/s
2052-Mar-10 19:01 0.135688 AU
20298684 km
5.50 km/s
2053-Jan-26 06:05 0.111466 AU
16675022 km
7.68 km/s
2054-Jan-14 09:29 0.292382 AU
43739774 km
14.11 km/s
2075-Sep-16 07:16 0.456707 AU
68322407 km
19.49 km/s
2076-Sep-07 23:54 0.255620 AU
38240141 km
13.41 km/s
2077-Sep-03 12:43 0.069079 AU
10334020 km
7.52 km/s
2078-Sep-30 07:08 0.109347 AU
16358020 km
4.87 km/s
2079-May-19 01:50 0.206643 AU
30913422 km
6.51 km/s
2079-Nov-17 16:11 0.170624 AU
25525003 km
5.03 km/s

Distances in astronomical units (AU) and kilometres. Source: NASA/JPL CNEOS Close Approach Data API.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
25.12

Orbit Quality

RMS
0.50456
Condition
5
Orbit ID
—
Data source: NASA JPL Small-Body Database · NASA CNEOS. Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

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